bogus wrote:
it sounds like the fans are NOT kicking in.

do they fire when the AC is turned on? they are supposed to.

I assume you have the 2 fans, one in front, one in back? If so, that's the heavy duty fan system.

With what you have, it sounds like the fans are my #1 blame at this time. Check the relays and hope.

I don't remember where the relays are on the 89... Matatk should chime in with that info.

Also, remove that 160stat, it won't fix this problem at all. In fact, it will make it worse.

Finally, check to be sure the rad is clear of debris, that will really kill it.

Durango_Boy wrote:
Does the fan have a shroud or is it just a fan bolted to the radiator? It sounds like you need more air flow, which to me means a stronger fan.

Also, have you tried any coolant additives? I played around with some constants on two of my configurations and I got some noticeable differences when I played with mixture and added a bottle or two of Water Wetter.

Right now, I add two bottles of Water Wetter to the empty system, then a perfect 50/50 mix of coolant and aluminum safe water.

Matatk wrote:
The upgraded single fan would be far superior to the auxiliary fan option.

bogus wrote:
too low a cap pressure and all bets are off.

Also, I am a fan (pun!) of dual small fans vs one big one. If one fails, at least the other keeps going.

But with your intercooler and such, one OEM fan just won't do...

WW7 wrote:
I may be a little late for the party, but here's my 2 cents on the problem..
On my 89 with the 383 I was having the same problem with temps when the A/C was on,my temps would keep climbing until I was forced to turn the A/C off. I installed a Dewitt's high speed fan and now I run about 210-215. The stock fan puts out 1700 cfm while the Dewitt's puts out 2360 cfm.The difference can be felt by putting your hand near the gills on the side where the air flows out, before I could hardly feel any air at all coming out,now with the Dewitt's fan the air is really moving. I also noticed the underhood temps are much lower because of all the air moving through faster, this also has to be better for all the plastic and rubber parts under the hood....WW

bogus wrote:
oh, dear.

Scott7 wrote:
Quote:

bogus wrote:
oh, dear.

Hi, I guess I don't understand the "check the OP's Scott7 address" comment from Flyboy. Could you tell me what this is referring to? Thx, Scott

bogus wrote:
Scott - judging from the fact that you are here today indicates you weren't effected by the theater shooting last week.

It was your connection to Aurora, CO that flyboy noticed.

So very sorry about the tragedy; thankful that you weren't hurt. I hope that thankful extents to your family and friends, too.

Matatk wrote:
Quote:

Scott7 wrote:
Quote:

bogus wrote:
oh, dear.

Hi, I guess I don't understand the "check the OP's Scott7 address" comment from Flyboy. Could you tell me what this is referring to? Thx, Scott

I didn't understand it either, don't feel bad.

Any update on your overheating issue?

Matatk wrote:
I was thinking about this post on the way home as I had my a/c on. Temp outside was around 100* depending on location. I was in mixed rush hour traffic on the surface streets and highway...from a crawl to 55 mph. I saw my temps creep up to 230 on the coolant but never got above 200 with the oil (Mobil 1 synthetic). Turning the a/c off brought the coolant back to 205-215 but never below that.

I don't have coated headers and I know that contributes to my underhood temps.

I think that the extra heat generated by the a/c might be overpowering the cooling system in general.

You have a supercharger, etc. Is any of that piping, headers, etc coated or wrapped?

I have been considering hood vents for a while to help reduce the temps underhood. I think evacuating that extra heat might be the only way to reduce the coolant temps.

Just me thinking out loud. Any updates on your fan upgrade?

Matthew

Matatk wrote:
Interesting that we both have uncoated headers. I think that contributes a lot to the underhood heat. Perhaps that large volume of heat soak that is under the hood is preventing the radiator from cooling well. Even with a fan blowing, I think it's picking up a lot of the hot air and just blowing that around. That retained heat may also be affecting the hoses and other portions of the system under the hood.

I agree there has to be a viable solution. I'm wondering if coated headers (and in your case wrapping the supercharger system) would be a great benefit?

Matthew

Matatk wrote:
And I'll be looking forward to hearing your impressions on the fan upgrade.

I normally have zero issues with overheating. I have a newer AC Delco radiator, new water pump, everything flushed when the new motor was put in, 180* stat, fans lowered, etc. On a cool day at cruise I run in the low to mid 180s, sitting at a long light I'll creep up to 210* or so. Start moving and it drops back down. On warmer days, I might run 195* at a cruise, same issue at traffic lights. Now that the a/c is fixed, I'm experiencing the coolant climb up to 230*.

Another thing to note is I know the fan normally turns off over 45 mph...I have to check the FSM to see if that is true if the a/c is on, as well. If that's the case, if we are still experiencing high temps at 45 mph+ with the a/c on, we need to shift our focus away from the fan cfm....and I think back to underhood temps.

Matthew

Matatk wrote:
Oh, and as far as "normal" operating range, the main fan on the L98s was not set to come on until the 228* range or so, the secondary fan was set to come on around 238* or so. The stock tstat is a 195*. These higher temps were used for emissions more than anything else. I don't like to run my car at 225* even though that's what they designated.

I have noticed that after my break in period when I switched to synthetic oil, the oil temps were much lower and more stable. I also noticed that bypassing my heater core lowered my coolant temps. I think it was gunked/clogged after 20 years before it finally sprung a leak.

Matthew

Scott7 wrote:


Yes I agree I like to run cooler but I found I was replacing the cat every two years, I've been told the lower temps were contributing to its failure. Since I switch over to dual exhast with bullet cats I've passed emissions twice so thats been a good improvement. These little cats are going on 4 years now. I've been using synthetic oil exclusively for many years, infact most of the car's life.

Matatk wrote:
Also, any pics of your hood vents?

Scott7 wrote:
Quote:

Matatk wrote:
Also, any pics of your hood vents?

I would really like to share some pics but unfortunately I'm having difficulties uploading. As soon as I get this worked out. . .

Scott7 wrote:
Quote:

Matatk wrote:
Also, any pics of your hood vents?

I would really like to share some pics but unfortunately I'm having difficulties uploading. As soon as I get this worked out. . .

Matatk wrote:
Thanks for sharing your experience. Unfortunately Scott already has a dewitt's radiator installed so that isn't the issue. We are leaning towards high underhood temps with limited air circulation as the main factor.

Matatk wrote:
Ray -

Thanks for the input. I agree that having coolant flow too quickly can cause overheating.

In my case, I have a standard GM radiator and standard flow water pump. My overheating is at idle or low speed....so the coolant isn't traveling through the system too quickly imho. Doing 55 mph with sufficient coolant flow and air flow in combination I do not experience the overheating problem. Because of this, I still theorize that too much trapped heat underhood is contributing to my problem.

jonszr1 wrote:
have any of you guys thought of going to an edelbrock water pump. have flow more water with a better balanced flow the dirt track guys swear by these things . since you have an 89 you have this option .